We investigate the magnetic field effects in thin-film diodes made of the conducting polymer poly(styrene-sulfonate)-doped poly(3,4-ethylenedioxythiophene) as a function of temperature and electrical current. Magnetoresistance of these devices can be measured to high precision on two distinct magnetic field scales: <3 mT, where a pronounced nonmonotonic magnetoresistance response can be resolved, owing to weak hyperfine coupling, and at intermediate magnetic fields, ranging between 3 and 10 mT, where strong monotonic magnetoresistance is seen. The detailed examination of the magnetoresistance effects in both regimes allows one to scrutinize the accuracy of the underlying models for the behavior of these kinds of materials. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.